I inherited a Linksys BEFSR81 8-port ethernet router that a previous
owner connected the wrong power adapter to. There is a 14 pin surface
mount IC identified as "U7" in the front left corner of the board which
had the magic smoke let out of it. I assume that this is just some cheap
bit of glue logic, and would be worth attempting to replace before just
trashing the whole unit. Unfortunately, the chip is so badly burned that
I can't get any identifying numbers off of it. Everything else seems in
good condition, and the unit even lights up and displays the config page
correctly (but won't route any packets), so hopefully this will be an
easy fix.

Does anyone have access to a schematic for this unit, or have one that
they could crack open and have a look at?

73,
Bob Weiss N2IXK

Meat Plow wrote:

Not to be smart but what makes you think a schematic would exist for this
thing?

The fact that someone somewhere designed the thing, and would want to
document their efforts in a form understandable to others?

I doubt anyone anywhere ever did a component lever repair on this
or any other Linksys unit.

Some Linksys products have quite a following in the "hardware hacker"
community. And call me a tree-hugging hippie freak, but spending 10
minutes soldering and a few cents for a part beats the hell out of
dumping a nearly new unit (which would cost ~$80 to buy new)into a
landfill...

Bob Weiss N2IXK

Thanks a bunch Steve!

Although the component designation numbers and layout are somewhat
different, the '123, '125, and '14 all correspond with the circuitry in
my unit, so my burned chip is most likely an 74HCT04. As I suspected, an
el-cheapo logic gate which I should have in stock. Will swap it out and
hope for the best.

Thanks again!

Bob Weiss N2IXK

Steve Sousa wrote:

Hello:

I took a pic of my befsr41, your 81 might be similar.
However when a surge blew my router it was perfectly functioning except
for the wan side, it turned out to be the rtl8019, i replaced it and has
been working since, those small chips were only for the leds...

Good luck

Steve Sousa

An update:

Chip replaced with 74HCT04, router working fine.

Thanks, Steve!

Bob Weiss N2IXK


Bob Weiss wrote:
Thanks a bunch Steve!

Although the component designation numbers and layout are somewhat
different, the '123, '125, and '14 all correspond with the circuitry in
my unit, so my burned chip is most likely an 74HCT04. As I suspected, an
el-cheapo logic gate which I should have in stock. Will swap it out and
hope for the best.

Thanks again!

Bob Weiss N2IXK

Steve Sousa wrote:

Hello:

I took a pic of my befsr41, your 81 might be similar.
However when a surge blew my router it was perfectly functioning
except for the wan side, it turned out to be the rtl8019, i replaced
it and has been working since, those small chips were only for the
leds...

Good luck

Steve Sousa